1. Field of the Invention
The present invention relates to a wireless power feeder, a wireless power receiver, and a wireless power transmission system for transmitting power by a non-contact method.
2. Related Background Art
Japanese Patent Application Publication No. 2010-22076 discloses a non-contact power transmission apparatus (wireless power transmission system) which performs power transmission by a non-contact method from a primary side coil (power feed coil) to a secondary side coil (power receive coil) using an electromagnetic induction, which is one type of magnetic coupling (electromagnetic coupling). In this non-contact power transmission apparatus, a primary side coil is driven by AC voltage on the basis of the output of a oscillation circuit. The oscillation circuit is a variable-frequency oscillation circuit of which the oscillation frequency can be varied. This non-contact power transmission apparatus detects an input power supplied from a power source to the primary side coil, finds the oscillation frequency at which the input power becomes a maximum, and operates the oscillation circuit at that oscillation frequency. By this means, decline in the power transmission efficiency due to component variation or positional deviation of the coils is avoided, and the transmission efficiency can be improved.
More specifically, the non-contact power transmission apparatus disclosed in Japanese Patent Application Publication No. 2010-22076 comprises a voltage detection circuit for detecting an input voltage, a current detection circuit for detecting an input current, and a multiplication circuit for calculating the product of the output of the voltage detection circuit and the output of the current detection circuit.